138 Phelps and Weed — Acids and Acid Anhydrides. 



Art. XVI. — Concerning Certain Organic Acids and Acid 

 Anhydrides as Standards in Alkalimetry and Acidimetry y 

 by I. K. Phelps and L. H. Weed. 



[Contributions from the Kent Chemical Laboratory of Yale Univ. — clxxix.] 



In a former paper* from this laboratory it has been shown 

 that, with cochineal as an indicator, succinic acid may be used 

 as a standard for a decinormal ammonium hydroxide solution 

 quite as accurately as may a decinormal solution of hydro- 

 chloric acid, the standard of which is determined gravimetri- 

 cally as the silver chloride. In this paper results are given 

 which show that, in presence of phenolphthalein as an indica- 

 tor, pure sodium hydroxide in solution and also pure barium 

 hydroxide in solution may be determined similarly with suc- 

 cinic acid, succinic anhydride, malonic acid, benzoic acid, 

 phthalic acid and phthalic anhydride, as standards. And, 

 further, it is shown that these organic acids and acid anhydrides 

 react with these alkaline solutions so that each may be used as 

 a standard in acidimetry and alkalimetry with the same exact- 

 ness that is found when these alkaline solutions are titrated 

 in the well established manner with decinormal hydrochloric 

 acid, standardized gravimetrically as silver chloride. 



For the work given here a solution of hydrochloric acid 

 was made up approximately decinormal by diluting the chem- 

 ically pure acid of commerce in the usual manner. The 

 exact strength of the hydrochloric acid solution was deter- 

 mined by precipitating definite amounts of it in a platinum 

 dish, in some cases, and in a glass beaker, in others, by an 

 excess of silver nitrate, in presence of a few drops of dilute 

 nitric acid. In each case the precipitate of silver chloride 

 was allowed to stand for twenty- four hours before filtering on 

 a weighed asbestos felt in a perforated platinum crucible. 

 The volume in which the silver chloride was precipitated was 

 such that after the precipitation was made it amounted to about 

 250 cubic centimeters. 



The sodium hydroxide solution was made up to correspond 

 approximately to the hydrochloric acid solution, by diluting 

 with distilled water, freshly boiled, pure sodium hydroxide, 

 prepared by the action of water vapor on metallic sodium 

 according to the, method of Kiister.f The barium hydroxide 

 was prepared pure by crystallizing twice commercial barium 

 hydroxide out of hot water, washing the crystals after each 

 purification with alcohol. A solution, approximately decinor- 

 mal, was made by dissolving these crystals in a suitable amount 



* This Journal, xxiii, 211. 



f Zeitschr. anorg. Chem., xli, 474. 





